Property  of  the  Unii:  .   Coven. 


:ular  No.  80. 


United  States  Department  of  Agriculture, 

BUREAU    OF    ENTOMOLOGY, 
L.  O.  HOWAHU.  Kntomologiit  and  CInct  ul    Hurciu. 


1111     ■ILOft     \rniv 

| 
I       II     ClIITTI  KDKN, 

uii;:     OF    ITTACK. 

The  melon  aphis,  or,  as  it  is  commonly  known,  the  "melon  touse," 
injures  plants  h\  piercing  them  with  it-  beak  and  sapping  their  vital- 
ity. It  occurs  from  early  spring  to  late  in  autumn  <>n  melons  and 
other  cucurbits  <»t'  all  kinds,  and  on  many  other  crop  plants,  and  in 
as  which  favor  its  increase,  notably  in  summers  following  springs 
that  are  cool  and  rainy,  it  frequently  develops  in  enormous  numbers 
and  does  \i'!\  serious  damage,  collecting  in  masses  on  the  under  sur- 
■  \  the  leaves  of  plants  and  causing  them  to  curl,  shrivel,  and  lose 
coldi',  and  interfering  with  the  ultimate  development  of  the  fruit. 
Often  it  kills  plant-  outright,  and  destroys  whole  fields  ot  greatly 
reduces  the  \  ield  of  fruit  An  affected  cantaloupe  plant  is  illustrated 
l>\  figure  1 . 

The  melon  aphis,  like  ot  her-  of  it-  Kind,  excretes  "honej  dew,'1  l»ut 
this  i-  not  so  copious  as  in  the  case  of  many  species  of  aphides,  for 
example,  eei  tain  forms  which  affect  tree-.  When,  however,  the  aphis 
under  discussion  becomes  unusually  abundant,  the  honey  dew  covers 
the  leaves  of  the  affected  plant-  with  a  thin,  sticky  coating  on  which 
the  white  ea-t  -kin-  of  the  aphides  adhere,  and  this  attracts  attention 
to  injury,  as  doe-  al-<>  the  wilting  and  dying  down  of  the  plant-. 
Some  persons  notice  this  honey  dew.  and  are  unaware  of  the  presence 
of  the  insects.  They  speak  of  the  injury  as  •"honey  dew."  and  have 
even  applied  thi-  name  to  the  insect  itself. 

Quite  too  frequently,  by  the  time  the  presence  ot'  the  melon  aphis 
in  injurious  numbers  is  noticed,  irreparable  damage  ha-  been  accom- 
plished and  the  insects  ha\e  for  the  most  put  migrated  to  other 
pastures. 


iik  by  many  forma  ol  aphides,  especially  those  which  excrete  honey  dew 
more  copiously,  can  be  readily  detected  by  the  presence  of  insects  which  feed  on  the 
tion.      kmong  the-.'  are  flies,   wasps,   bees,  and   especially  ants.     The 
melon  a  phi-,  however,  i-  not  an  especial  favorite  with  ants,  altho  some  common  -]*•- 
illy  found  in  attendance  upon  it.     The  pavement  ant     '/ 
the  "iily  8]  r  been  observed  by  the  writer,  and 

neither  ant  m >r  aphis  appears  to  In-  in  any  way  dependent  on  the  other  I 
once,  contrarj  to  that  which  i-  the  case  with  many  other  aphides,  particularly  those 
which  have  root-feeding  forms. 

[0248      \      -.»— Oti 


s%$$ 


DESCRIPTION. 

The  melon  aphis  fa.  minute,  soft-bodied  creature, of  liable  color 
usually  oi  some  shade  of  green  or  greenish  black;  in  its  young  and 
wingless  stages,  louselike  in  appearance;  and  of  sluggish  habit  thru 
out  its  existence     The  general  appearance  of  this  splSes  in  ite  most 
commody  observable  stages  is  indicated  in  figure  2,  highly  magnified 
A  brief  description  of  the  stages  figured  will  suffice  for  the  present 

purpose. 

The  coo-  has  been 
described  by  Mr.  Th. 
Pergande"  us  of  regu- 
larly oval  shape  and 
measuring  about  0.6mm 
in  length;  yellowish 
<>r  greenish  when  first 
deposited,  soon  chang- 
ing to  jet  black. 

The  larval  aphis  or 
nymph  (fig.  2,  b)  when 
first  born  or  hatched 
presents  no  observable 
characters  for  com- 
parative description. 
It  measures   less  than 

0.5 and   is    pale   in 

color,    turning     |;lter 
to    yellow.    The   hist 
nymphal  stage,  corre- 
sponding to  the  pupa 
of    other    insects,    is 
sufficiently  illustrated 
at  c  that   it  requires 
no  verbal  description. 
The  apterous  or  wing 
le->    female,    which   is 
viviparous    ( gi  v  i  n  g 
birth  to  living  young), 
is  figured  atrf.    Great 
variation  is  exhibited  in  this  stage,  from  pale  yellow  to  very  dark  green 
with  black   nectaries  or  honey  tubes  and  pal'e  whitish-yellow  lees  and 

antenna'.      This  stage  varies  i„  length  from  1.5  to  l.s The  winged 

female  is  illustrated  at  <z,   which  shows  a  form   with  pale  abdomen. 
1  he  body  ,s  more  slender  than  in  the  wingless  form,  the  length  being 

-Insect  Life,  Vol.  VII,  ,,,,  309-315,  1895.     Technical  descriptions  are  furaisl 
al>,,  bj  Forbes,  12th  Rept  St.  Km.  111.  f.  1882  |  1883),  pp.  83-91. 


Pig.  1. -cantaloupe  leaves  showing  curling  eaused  by  melon  aphia 
aphideson  lower  surface.    Slightly  reduced  (original). 


8 

from  1  .■_'  to  I . v  .  while  the  wings  expand  from  I .  ■■  to  6  '  \  darker 
form  of  the  female  is  shown  in  profile  at  ab,  and  the  antenna?,  much 
enlarged,  ;it  an.     The  male  has  no(  as  yel  been  recognized. 

This  i-  l>\  far  the  moa(  important  and  abundant  aphis  affecting 
1 1 k •  I « » 1 1 -  and  other  cucurbits,  and  is  m>t  I i k » ■  I \  ii>  be  confused  with  am 
other  species  occurring  habitual  I3  on  the  same  classof  plants.  Ii  i>. 
indeed,  a  vev\  important  pest,  and,  taken  season  after  season,  the  worst 
aphis  occurring  in  this  count r\ . 

ad 


A**5 


1  aphis      1  winged  female;  aa,  enlarged  antenna  ol  Bame   ofr,  dark 

^iiii;  juice  from  surface  of  leaf;  b,  young  nymph  or  larva;  r,  last  - 
nymph;  •/.  wringl  Allgreatlj  enlarged  (author's  itlustrai 


DISTRIBT   [ION. 

The  origin  of  the  melon  aphis  is  doubtful,  but  is  probably  tropical, 
Bince  ti»i—  insect  shows  a  decided  preference  for  plant- of  a  tropical 
nature,  such  as  the  cucurbits,  cotton,  and  orange.  Southward  the 
aphis  occurs  in  the  West  Indies,  in  Mexico,  and  in  Brazil,  and  doubt- 
less elsewhere  in  South  America.  It  is  very  generally  distributed 
tlmiout  the  United  States,  l>ut  dor-  more  injury  in  the  southwest  than 
elsewhere.  In  Texas,  Kansas, and  Nebraska  it  i-  particularly  trouble- 
some to  melons,  and  in  the  last  two  States  t<>  cucumbers,  which  are 
there  extensively  grown  for  pickling.     Bui  it  ma\  at  any  time  create 

"The  squash  aphis  \  '■'■  ophora  [Siphonophora]  ctttwbiUe  Middleton),  a  much 
larger  species,  more  uniformly  green,  and  of  a  moch  lighter  and  brighter  color,  is 
often  Found  on  cucurbits,  bat  seldom  in  sufficient  numbers  to  cause  noticeable 
damage 


more  or  less  trouble  in  northern  regions,  particularly  in  Virginia, 
Maryland,  Delaware,  and  New  Jersey,  where  cucurbits  are  much  cul- 
tivated. Occasionally  it  is  injurious  as  far  north  as  Minnesota  and 
west  to  California.  It  has  been  collected  also  in  Adelaide.  South 
Australia. 

INSTANCES    OF    INJURY. 

The  melon  aphis  first  attracted  notice  thru  its  injuries  to  cotton  in 
1854,  and  from  that  time  on  it  has  done  more  or  less  damage  year  by 
year,  and,  in  view  of  its  rapacity,  rapid  multiplication,  and  omnivo- 
rous habits,  will  no  doubt  continue  injurious  in  spite  of  all  that  can 
be  done  to  repress  it.  As  a  melon  and  cucumber  pest  it  was  noticed 
in  Florida  and  southern  Illinois  in  1880,  and  in  the  next  three  years 
caused  considerable  losses  in  those  States  and  in  Georgia.  Soon  after- 
wards it  became  recognized  as  a  strawberry  pest.  In  later  years  many 
other  food  plants  were  added  to  its  known  dietary.  The  years  1892, 
1893,  and  1898  were  unusually  bad  ''aphis  years." 

In  1893  information  was  received  from  a  pickle  company  of  Omaha. 
Nebr.,  of  severe  injury  in  that  State.  This  company  was  growing 
between  30,000  and  50,000  bushels  of  cucumbers  a  year,  and  sev- 
eral hundred  neighboring  farmers  grew  this  vegetable  for  the  com- 
pany. Two-thirds  of  the  crop  grown  in  1892  was  destroyed  by  the 
aphis,  and  in  1893  half  of  the  crop  was  lost.  These  injuries  made  it 
difficult  to  induce  outside  planters  to  grow  for  the  company. 

In  1898  this  species  was  extremely  troublesome.  In  order  that  a 
good  idea  of  its  destructiveness  may  be  had.  some  reports  are  cited. 
In  January  injury  was  reported  on  cucumbers  in  Florida  and  in  May 
to  strawberries  in  Delaware,  where  the  insects  were  described  as 
"taking  everything  clean. r  By  June  this  insect  had  been  very 
injurious  to  watermelon  in  southern  Texas,  when  it  destroyed  many 
acres  of  early  vines.  In  July  Texas  correspondents  reported  the 
destruction  of  1,001)  acres  of  cantaloupes  in  one  locality,  and  the  out- 
break assumed  such  proportions  as  to  cause  much  newspaper  com- 
ment. One  company  reported  that  the  ravage.-  of  this  pest  had  cost 
them $20,000,  and  that  agriculturists  of  that  section  had  sustained  irre 
trievable  loss.  In  November  a  Pennsylvania  correspondent  reported 
losses  to  cucumbers  grown  under  glass,  and  in  December  this  aphis 
resumed  its  ravages  to  cucumbers  in  Florida. 

LIST   OF   FOOD    PLANTS. 

The  insect  here  considered  is  the  most  nearly  omnivorous  of  any 
known  species  of  aphis.  The  list  of  plants  upon  which  it  has  actually 
been  found  feeding  shows  great  diversity,  and  future  observations 
may  add  many  more  host  plants. 

It  is  partial  to  the  plants  that  have  previously  been  mentioned — 
melons  and  other  cucurbits,  cotton,   okra,  orange   and   other  citrus 


fruit-,  strawberry,  and  purslane     but   it  attacks  also  clover,  beans, 
beeta,  spinach,  tomato,  bops,  and  pear,  and  several  ornamental  plants, 
including  hydrangea,  begonia,  ground    i\\    [Nepeta  glechoma),    \    i 
lypha,  and  morning-glory.     From   its  abundance  on  some  of  these 
plants  it  has  received  n  number  of  common  as  well  as  Latin  synonym 
ical  names,  the  former  including  cotton  aphis,  orange  aphis,  cucumber 
louse,  and  cantaloupe  louse."     It  in  frequently  called  also  the  " black 
aphis,"  especially  in  its  occurrence  in  greenhouses.     Mr.  Pergande  has 
found  it  feeding  upon  n  large  number  of  weeds,  among  which  are  shep 
herd's  purse,  pepper  grass,  pigweed  i  Imaranthus),  dock  (Rumex),  bur- 
dock (Arctium),  dandelion,  lambsquarters  (Chenopodium),  plantain, 
chickweed,    button-weed   (Diodia),    mallow,    dogwood   (Cornus),   and 
Jamestown  or  jirason  weed  (Datura). 

Since  these  aphides  are  not  at  all  particular  as  to  their  food,  when 
thc\  migrate  from  their  favorite  plant-  they  -tart  colonies  on  nearly 
an\  plant  that  chance-  to  he  in  their  line  of  flight.  The  writer  has 
-ecu  asparagus  and  violet  attacked,  the  hitter  >jr<>\\  n  in  greenhouses. 

i  11  i.    1 1 1-1 1  >i:\  . 

Attack  to  cultivated  plant-  begins  from  early  spring  till  consider- 
ably later,  and  i- made  by  winged  individual-  flying  from  weeds  which 
serve  as  alternate  food  plants.  Infestation  naturally  commences  earlier 
in  the  South  than  northward,  and  ma\  be  simultaneous  with  the  appear- 
ance of  the  crop  above  ground.  Soon  after  the  plant-  have  developed 
leaves  a  few  winged  aphides  can  usually  be  found,  and  these  are  the 

forerunner-    of    myriads    to    follow.      A-    often    a-    a    plant    becomes 

exhausted  of  it-  vital  juice-  by  the  sucking  mouth  part-  of  innumera- 
ble aphides,  winged  individuals  are  developed  which  migrate  to  other 
plant-,  -o  that  migration  in  the  case  of  thi-  species  i-  carried  on  prac- 
tically thruout  the  season.  Flight  from  one  kind  of  food  plant  to 
another,  or  from  one  field  to  another,  i-  caused  also  by  disturbance 
from  the  abundant  natural  enemies  of  the  insect.  The  great  num- 
bers of  thi-  species  sometimes  suddenly  discovered  on  melon-,  cotton. 
orange,  and  other  plant-  are  often  due  to  en  forced  migration  on  account 
of  the  death  of  other  food  plant-  in  the  vicinity,  such  a-  might  !>•• 
caused  bj  atmospheric  condition-,  or  bj  the  ravages  of  the  aphides 
themselves,  or  of  other  insects.  The  removal  of  the  crop  on  which 
the  insect  was  at  work  will  produce  the  same  effect. 

\  \  1 1  i:  \t.   i:\i  mm  -. 

There  i-  perhaps  no  'better  example,  among  insects,  of  a  common 
and  widespread  species  being  held  in  abeyance  and  limited  to  innoxious 

"The  synonyms incladi  Stphonophora)  cilri/olh  Ashm.,  Aphis  citrulii  A-lnn., 

Aphii  Forbes,  Aphis forben  Weed.     It  i-  -till  mentioned  in  literature  a- 


numbers  (save  in  exceptional  seasons)  by  natural  enemies  than  the 
melon  aphis.  The  usefulness  of  these  natural  enemies,  of  which  a 
large  number  have  been  recorded,  in  subduing  the  aphides  can  not  be 
overestimated.     Garden  and  field   aphides   generally  are  subject  to 

attack  by  the  same  classes  of  parasitic  and  predaceous  enemies.  The 
number  of  species  of  insects  known  to  prey  upon  the  melon  aphis  is 
about  35.  The  list  includes  many  ladybirds  or  "ladybugs"  (Cocci- 
nellida')."  which  destroy  the  aphis  both  as  beetles  and  a>  larva",  the 
maggots  of  certain  syrphus-flies  (Syrphidae),*  which  consume  large 
numbers  of  aphides;  aphis  lions — the  larvae  of  lace-wing  flies,  of  the 
families  Chrysopidse  and  1  [emerobiidae."  A  number  of  species  of  para- 
sitic insects,  chiefly  minute  forms  of  Braconidae,  are  also  very  impor- 
tant checks  on  the  increase  of  aphides.''  Many.  too.  are  destroyed  by 
parasitic  fungi. 

The  insect  enemies  of  these,  as  of  other  aphides,  keep  their  hosts, 
in  many  portions  of  the  country  and  in  ordinary  seasons,  in  nearly 
complete  subjection.  The  parasites,  in  particular,  are  most  effective 
in  dry,  warm  weather.  In  cooler,  moist  summer  weather,  especially 
following  t/t,  x<i n ic  atmospheric  conditions  in  spring,  when  vegetables 
subject  to  aphis  injury  are  starting  growth,  these  otherwise  natural 
checks  are  less  active,  and  the  aphides,  as  a  result,  frequently  gain  the 
ascendency. 

Some  of  the  commonest  species  of  ladybird  enemies  of  this  and 
other  aphides  are  illustrated  in  figure  3.  In  the  "aphis  year"  of  1898 
the  Scymnus  (tig.  3,  //,  i,j)  was  particularly  abundant  in  and  near  the 
District  of  Columbia  on  aphis-affected  plants.  A  still  more  abundant 
and  useful  form  of  this  class  of  insects  is  the  convergent  ladybird 
{Hippodamia  convenjriis  Guer.),  shown  in  fig.  3,  '/.  &,  c.     It   is  fre- 

"  Hippodamia  convergens  (iuer.  and  Oycloneda  sanguined  I.,  are  prominent  enemies, 
as  are  also  Megilla  maculata  De  <l.  i  lij_r.  •'■!,  '/,  e)  and  Coccinella  9-notata  llhst.  <  >ther 
species  are  Sci/mim*  terminatus  Say,  S.  caudalis  Lee.  S.  cervicalis  Muls.  (A), 
Chilocorus  biindnerus  Muls.,  Exochomiis  constristaius  Muls.  (H),  and  Hippodamia 
lS-punctata  L. 

f'Syrphus  flies  include  Syrpkus  americanus  Wied.,  AUograpta  obliqua  say.  Baccha 
clavata  Fab.  {babista  \Valk.),i?.  lugens  Loew.  (H),  /.'.  cognata  I. new.  (H),  11.  fusd- 
pennis  Say  (A),  and  Eupeodes  volucris  <  >.  S.  An  agromyzid  fiy,  Leucopis  nigricorni* 
Egger,  also  preys  on  this  aphis.  Cecidomyiid  enemies  include  certain  undetermined 
species  of  Contarinia  (Diplosis  ). 

o  Among  the  lace-wing  flies  are  Chrysopa  oculata  Say,  C.  plorabunda  Fitch,  C.  alUn- 
cornis  Fitch  (A),'',  nigricornis  Burm.  (A),  C.  lineaticornw  Fitch  (A),'',  attenuata 
Walk.  (A  ).  Micromus  posticus  Walk.,  ami  Hemerobius gossypii  Ashm.  (A). 

tf  Parasitic^braconids  include  Trioxys  testaceipes  Cress.,  Lysiphlebus  gossypii  Ashm., 
/..  citraphis  Ashm.,  L.  cucurbitaphis  Ashm.,  /..  minutus  Ashm.,  Lysiphlebus  sp.,  and 
Pachyneuron  sp.     A  chalcis  fly,  Stenomesiw  aphidicola  Ashm..  lias  also  been  reared. 

The  species  followed  by  ( II  i  were  observed  attacking  Aphis  gossypii  on  orange  trees 
in  Florida  by  II.  <i.  Hubbard,  those  marked  i  A  |  by  Win.  II.  Ashmead  on  cotton  in 
Mississippi.  The  others  are  mostly  well  known,  and  have  been  observed  by  various 
persons,  as  well  as  by  the  writer. 


( 1 111 'tit  I  \  mistaken  for  the  parent  of  the  aphides.     Another  >  en  efficienl 
enemy,  the  nine  spotted  ladyhird,  is  shown  in  figure  3,  f. 
One  of  the  mosl   abundant   sryrphus-frj    enemies   i-  illustrated   bj 

li'Mllr    I. 


fa*>^S& 


Of  the  nataral  enemies  which  have  been  enumerated,  ladybirds  are 
particularly  valuable,  owing  principally  to  the  fact  that  the}  are  active 
al  all  seasons,  especially  at  the  outset  of  aphis  attack.  Parasites  are 
most  effective  toward  the  end  of  the  season,  when  they  often  reduce 


the  aphides  so  thai    few  arc  left  to  hibernate  and  produce  other  gen- 
erations of  the  pest  the  following  year. 

The  value  of  these  natural  enemies  against  aphides  is  such  that 
entomologists  frequently  advise  the  employment  of  remedies  only 
when  the  enemies  are  not  present  in  abundance.  Tlie  possible  utiliza- 
tion of  natural  enemies  in  the  field  will  he  considered  on  page-,  15  and 
16  of  this  circular.  In  tobacco  fumigation,  which  will  presently  lie 
considered,  we  have  an  almost  ideal  remedy,  for  the  reason  that,  while 
aphides  are  all  destroyed,  a  considerable  proportion  of  the  ladybirds 
and  other  hardy  beneficial  insects,  which  are  practically  always  present 
on  the  infested  vines,  survive  this  treatment. 


Fig.  1.— A  syrphus-fly  (Syrphus  ribeaii):  a,  fly:  h.  lateral  view  of  head:  r.  larva  or  active  immature 
form;  '/,  anal  spiracles:  i .  thoracic  spiracle  of  same.    All  much  enlarged  (original). 

METHODS   OF   CONTROL. 

The  severe  losses  occasioned  by  the  melon  aphis  in  its  seasons  of 
greatest  destructiveness  could  he  largely  mitigated  and  in  many  cases 
almost  entirely  prevented  if  the  employment  of  methods  for  its  con- 
trol were  begun  upon  the  insect's  first  appearance.  For  its  successful 
treatment  it  is  necessary  to  keep  constantly  in  mind  several  of  the 
facts  that  have  already  been  given  more  in  detail.  In  ordinary  sea 
sons  the  species  is  controlled  by  the  combined  operation  of  natural 
elements  and  insect  enemies,  but  at  times  when  the  weather  is  unfa- 
vorable to  the  development  of  these  enemies  the  grower  should  be  on 
the  alert.  The  presenceof  the  aphides  is  often  not  detected  until  they 
are  numerous,  and  even  then  they  are  not  apt  to  be  noticed  unless  the 
Inn-, ,■  surface  of  the  leaves  be  examined. 

All  things  considered,  the  most  satisfactory  way  of  controlling  this 
insect  is  by  fumigation.  As  an  aid.  however,  cultural  methods  are 
necessary.  In  the  South  spraying  with  kerosene  and  other  emulsions 
is  preferred  to  the  bisultid  of  carbon  method,  and  tobacco  is  now  much 
used,  especially  in  Texas.  The  encouragement  of  natural  enemies 
gives  promise  of  success. 


HIM    I  I  II'    .il      i    VKII'iN      II    Ml'.  \  I  l"\ 


This  treatment  of  the  melon  aphis  has  been  used  successfully  for 
Borne  time,  and  i-  valuable  in  small  fields,  but  less  profitable  where 
cucurbit  or  other  crops  are  grown  over  large  areas.  It  consists  in 
evaporating  hisulnd  of  carbon  under  tubs,  or  similar  ti<_dit  receptacles, 
Buch  a-  pail-,  buckets,  or  boxes.  The  chemical  is  employed  ai  the 
rate  of  a  dram  (about  n  teaspoonful)  t«i  each  cubic  foot  of  space;  ;i 
tablespoon ful  will  serve  for  ordinary  small  tubs.  This  method  of 
treating  the  plant  does  not  injure  it.  and  it'  the  tub  tit  tightly  t<>  the 
ground,  so  as  to  retain  the  vapor  of  tin-  bisulfid,  all  of  the  aphides 
which  are  covered  will  In-  killed.  This  method  maj  he  followed  sue 
cessfiilly  in  large  fields  it'  the  grower  Ik-  careful  t<>  watch  tin-  \  ines  for 
the  first  appearance  of  the  insects,  and  to  treat  Buch  hills  as  require 
fumigation,  remo>  ing  ami  destroy  ing  plant-  that  arc  badlj  affected  t<> 
prevent  the  spreading  of  the  insects  to  others. 

( '  w  1 1'  >N.  In  the  use  <>l  bisulfid  of  carbon  a-  a  fumigant  for  aphides 
the  usual  precaution  should  be  observed  not  to  expos*  //>■  fumes  to  fire. 
ill,  operators  must  nut  smok*  during  this  process!  A-  tin-  gas  is 
lifa\  ier  than  air  there  is  no  danger,  it'  ordinary  rare  i-  observed,  that 
the  funic-,  will  he  inhaled  by  human  beings. 

HYDRi  (CYANIC-ACID    i ,  \-    I  Kl  \  nil  M 

This  gas,  as  has  been  demonstrated  by  Prof.  K.  I».  Sanderson,  can 
be  u^-t\  in  the  field  in  much  the  same  manner  as  the  bisulfid  <»t'  car- 
bon, with  wooden  tubs  or  buckets.  It  has  not,  however,  been  adopted 
by  growers  and  we  do  not  recommend  it.  It  possesses  an  advantage 
over  bisulfid  of  carbon  in  that  the  cover  used  in  gassing  need  not  tit 
closelj  to  the  earth.  ( )n  t he  other  hand,  it  \a  decidedly  mor*  danger- 
ous  to  human  lift  inn/  must  therefor*  In  handled  with  th*  greatest  care! 

Asa  greenhouse  insecticide  this  gas  is  a  perfect  remedy  for  aphides 
and  other  small-  and  soft-bodied  insects.  It  i-  used  where  tobacco  is 
unsafe;  for  example,  in  violet  bouses,  violets  being  especially  subject 
to  ••-pot"  after  fumigation  with  tobacco.  The  method  of  applying 
hydrocyanic-acid  gas  is  described  in  Circular  No.  37  of  this  Office. 

I'YKl.l  ma  M     POWDKR. 

1\  rethrum  or  buhach  insect  powder,  administered  dry  with  a  pow- 
der bellows  to  the  lower  surface  <>f  leaves,  will  kill  the  insects,  altho 
these  sometimes  do  not  appeal-  to  be  affected  at  first.  A  second  or 
third  applieat ion  i-  sometimes  necessary.  This  i-  an  expensive  rem- 
edy and  can  not  J>e  used  with  profit  «>n  large  fields  <>r  on  plant-  with 
large  leaves,  like  squash. 

In  \.u  Jersej  and  <  Colorado  many  growers  simply  take  oul  and  bury  such  badly 
infested  plants  as  are  noticed  when  the  hills  are  turned  for  cultivation. 


10 

FUMIGATION    Willi    TOBACCO    PREPARATIONS. 

Tobacco  extracts  and  fumigating  powders  have  been  extensively 
used  for  a  number  of  years  by  florists  a-  fumigants  against  aphides 
and  other  insects  occurring  in  greenhouses,  such  as  white  fly,  thrips, 
and  other  small,  delicate,  and  soft-bodied  insects.  The  extracts  con- 
tain a  larger  proportion  of  nicotine  than  ordinary  decoctions  prepared 
by  steaming  waste  stems  and  powdered  tobacco,  and  are  therefore 
much  more  effective,  which  is  true  also  of  the  powdered  forms  of  nico- 
tine. A  number  of  these  preparations  are  on  the  market  and  are 
advertised  in  the  principal  florists'  journals  and  in  other  agricultural 
periodicals.  They  are  used  in  various  way-,  and  direction-  are  fur- 
nished with  the  packages  purchased.  The  liquid  preparations  vary  in 
strength  from  35  or  4<>  per  cent  up  to  80  to  85  per  cent  nicotine. 

FIELD    FUMIGATION"    WITH    TOBACCO. 

During  the  years  1904  to  1906  the  employment  of  tobacco  or  nico- 
tine preparations  in  destroying  the  melon  aphis  in  the  field  was  the 
subject  of  experiment  in  Texas  by  Messrs  ('.  E.  Sanborn  and  E.  D. 
Sanderson."  These  have  stated  to  the  writer  that,  judging  from  their 
experimental  use  of  this  method  and  its  practical  use  by  extensive 
growers,  it  bids  fair  to  become  the  best  method  of  dealing  with  the 
melon  aphis  in  its  occurrence  in  the  South.  The  process  is  in  brief 
the  fumigation  of  a  dry  preparation  under  a  cloth-covered  frame 
placed  over  the  affected  vines.  In  1905  and  1906  the  writer  found 
that  a  very  short  exposure  to  tobacco  fumes  killed  aphides,  when  other 
insect-,  such  as  thrips,  survived  a  considerably  longer  treatment. 

In  practising  this  method  Mr.  Sanborn  has  used  apparatus  substan- 
tially as  follows: 

Preparation  of  the  frame  and  cover. — For  vines  2  or  3  feet  long  he 
advises  a  light  frame  -4  by  6  feet,  supported  by  legs  8  inches  in  length. 
Lumber  three-fourths  inch  thick  and  -1  inches  wide  is  suitable. 
Strengthen  the  frames  by  connecting  the  ends  with  aero—piece.  Two 
diagonals  are  also  used  for  strengthening  the  frame  and  for  conven- 
ience in  handling,  the  latter  being  attached  after  the  cloth  cover  is  in 
position.  The  cover  is  of  muslin  of  a  cheap  grade  (7  or  8  cents  a 
yard)  and  sufficiently  compact  to  prevent  a  passage  of  gas  thru  its 
meshes  after  being  oiled.  Its  size  should  be  about  %1  feet  wider  and 
2  feet  longer  than  the  frame  which  it  covers.  This  is  sufficient  for  an 
8-inch  wall  and  a  4-inch  lap  to  the  ground.  Dirt  is  placed  about  the 
bottom  to  keep  the  gas  from  escaping  there. 

After  the  cloth  has  been  cut  and  sewed  into  the  sizes  desired  it  is 
saturated  in  a  vessel  of  linseed  oil  which  tills  the  pores.     It  is  then 

"An  experiment  with  tobacco  smoke  as  a  remedy  fortius  species  was  made  by 
Dr.  S.  A.  Forlies  in  Issl'.  The  result  was  not  a  perfect  success,  for  the  reason  that  a 
bee  smoker  was  used  and  the  smoke  was  blown  under  canvas  hay  cape  covering  the 
affected  plants.  Nevertheless  from  50  to  75  percent  of  the  aphides  were  killed  by 
Hi  minutes'  exposure. 


wrung  out,  slighth  dried,  and  placed  over  the  frame  and  held  in  place 
i>\  nailing  the  diagonals  to  the  frame  above  the  cloth.  A  gallon  of 
linseed  oil  i>  sufficient  for  rendering  four  covers  of  the  size  above 
specified  sufficiently  air  tight  for  tin-  method. 

The  number  '>i'  frames  for  use  depends  upon  the  degree  of  infesta 
tion  and  the  rapidity  of  the  operators.     Ordinarily  about    10  frames 
are  sufficient  for  one  man's  attention. 

pplication.  The  frame  is  placed  over  the  inf<  sted  plant. 
One  sheet  of  the  fumigating  preparation  is  torn  into  from  two  to  four 
or  more  equal  parts  (according  to  directions  <»n  the  package  or  as 
experience  maj  decide)  and  each  part  i -  put  in  r  tin  fruit  can  under 
the  frame  near  a  corner  and  then  ignited.  The  cans  are  perforated 
at  the  bottom  by  driving  a  large  nail  in  at  the  side.  It  is  well  to  use  a 
long  taper  or  fuse  for  lighting  the  fumigant,  affording  the  more  active 
beneficial  insects  time  to  escape  from  under  the  cover  before  the  tobacco 
fumes  are  >_:i\<'n  off.  Earth  is  then  heaped  on  the  border  of  tin-  cloth 
on  the  ground  to  prevent  the  escape  of  the  smoke.  The  frame  should 
remain  in  position  ten  <>r  fifteen  minutes,  or  longer  if  preferred.  Each 
operator  - 1 » <  >  1 1 1  *  1  have  enough  frames  to  handle  so  that  each  frame  in 
-ii.-. 'c--ii>n  may  remain  on  a  vinr  during  the  time  mentioned. 

In  localities  where  the  aphis  is  most  injurious  local  merchants  who 
deal  in  insecticides  Bhould  be  informed  of  the  fact  and  requested  to 
keep  a  supply  of  fumigating  preparation  always  in  stock. 

The  best  time  for  fumigating  is  when  there  is  qo  wind  ami  the  vines 
air  damp.  In  moderately  dry  weather,  however,  good  results  maj 
be  obtained. 

Caution.  Care  should  be  exercised  not  to  allow  the  dry  fumigant 
to  ignite.  Lt  should  smolder  only.  Vines  should  not  be  disarranged 
except  where  they  protrude  a  few  inches  beneath  the  cover.     The 

lra\  es  should  not  touch  the  top  of  the  rover. 

Variations  ",'///•  fumigating  frame.  The  frame  described  above 
has  been  used  in  the  fumigation  of  young  plant-  in  southern  Texas. 
The  size  and  make-up  of  the  frames  maj  be  altered  or  inipro\  ed  l>\  the 
individual  grower  to  adapt  them  to  the  size  of  tin-  vines  and  the  nature 
of  the  plant  to  be  fumigated.  Farther  north  than  Texas  manifestation 
of  injury  is  not  usually  observable  until  the  plant-  have  made  consid- 
erably larger  growth,  and  a  larger  frame,  say  about  a  foot  high,  will 
be  found  more  desirable  for  general  use.  Unbleached  cotton  of  com- 
pact mesh,  at  1M  cents  a  yard,  answered  a-  well  a-  the  oiled  "muslin" 
in  experiments  conducted  by  the  writer,  and  their  is  a  saving  of  time 
in  its  use.  Moreover,  it  doe-  not  collect  dirt  nor  -oil  the  clothing  and 
other  objects  with  which  it  comes  in  cont 

For  the  treatment  of  plants  other  than  cucurbits,  such  a-  cabbage 
affected  by  the  cabbage  aphis,  eggplant,  tomatoes,  and  other  truck 
Mr.  Sanborn  advises  a  hood,  using  a  frame  made  of  two  wire-  Kent  in 
a  semicircle.  Strong  barrel  hoop-  ma\  be  substituted,  and  the  cover 
tacked  to  them  at  the  top  where  they  cross  and  at  the  bottom  of  the 


12 

hoops.  ( )rnamental  plants  of  low-growing  sorts  may  bo  fumigated  by 
means  of  such  a  hood,  while  for  moderately  high  plants,  such  as  rose-, 
which  are  much  affected  by  two  common  species  of  aphides,  special 
covers  may  be  constructed. 

VAPORIZING    AND    FUMIGATING   TOBACCO   IN   GREENHOUSES. 

In  the  vaporization  of  tobacco — a  practise  which  has  been  in  use 
since  about  lsi'4-and  which  has  largely  superseded  ordinary  dry-tobacco 
fumigation  in  many  sections  tobacco  stems  or  dried  tobacco,  in  one  or 
another  of  its  various  proprietary  forms,  are  placed  in  a  kettle,  metal 
pail,  or  similar  receptacle.  A  hose  is  then  connected  with  a  steam 
pipe,  the  nozzle  inserted  in  the  receptacle,  and  the  house  to  be  treated 
becomes  saturated  with  the  vapor  of  tobacco,  with  the  resulting 
destruction  of  aphides  and  other  soft-bodied  insects  that  may  be  pres- 
ent, such  as  thrips  or  "white  fly." 

Liquid  preparations  are  more  generally  evaporated  over  alcohol  or 
other  lamps,  or  are  placed  upon  steam  pipes,  or  hot  irons  are  put  into 
the  receptacles.  For  general  greenhouse  fumigation,  fumigating 
powders  are  placed  in  shallow  pans,  and  a  few  drops  of  kerosene  are 
added  to  facilitate  ignition.  The  dry  fumigant  is  designed  to  burn 
slowly,  so  as  to  produce  a  smudge  which,  when  dense,  is  fatal  to 
aphides.  This  process  of  treatment  may  be  applied  at  any  time,  by 
day  or  over  night,  and  upon  its  completion  the  house  is  ventilated.  In 
some  cases  the  plants  are  syringed,  but  this  is  not  necessary  with  plants 
like  cucumbers.  A  surplus  of  moisture  is  to  be  avoided,  owing  to  the 
liability  of  inducing  "spot,"'  mildew,  and  other  fungous  diseases  on 
plants  susceptible  to  such  maladies. 

The  amount  of  a  tobacco  compound  to  be  used  depends  upon  its 
strength,  the  plants  to  be  treated,  and  the  size  of  the  greenhouse.  Sev- 
eral forms  are  for  sale  under  different  trade  names.  It  is  not  probable 
that  these  differ  greatly  from  one  another  in  value,  but  there  is  much  dif- 
ference in  their  strength.    They  are  put  up  in  both  dry  and  liquid  forms. 

In  experiments  conducted  on  greenhouse  cucumbers  at  the  Massa- 
chusetts Agricultural  Experiment  Station,  at  Amherst,  one  of  these 
preparations  has  been  used  successfully  at  the  rate  of  5  or  6  teaspoon- 
fuls  to  1^  pints  of  water,  and  vaporized  in  a  space  of  about  5,000  cubic 
feet.  The  length  of  exposure  in  this  case  was  over  night.  Thus  used. 
it  does  not  injure  delicate  plants,  like  cucumber,  but  it  kills  all  aphides 
and  nearly  all  thrips — for  which  it  was  used  primarily  and  which  are 
not  infrequently  associated  with  aphides  on  the  plants  to  be  treated." 

"Thrips  ami  "white  fly"  (Aleyrodea  spp. )  are  more  resistant  to  poisonous  gases 
than  are  aphides;  The  former  are  must  effectively  destroyed  while  in  the  soft  imma- 
ture stages.  The  adult  thrips  are  hardier  and,  being  winged  and  more  active,  spring 
and  fly  away,  and  are  thus  not  SO  easily  brought  in  direct  contact  with  insecticides 
like  kerosene  emulsion.  The  white  flies,  on  the  other  hand,  are  more  susceptible 
t<>  poisons  while  in  the  active  adult  stage.  The  nymphs  are  of  firmer  consistency 
and  comparatively  resistant.  Remedies  for  the  greenhouse  white  tlv  are  discust  in 
Circular  No.  57. 


ta 

Tobacco  in  fine  powder  form  dusted  lightlj  <>n  verj  young  plants 
Berves  both  as  a  repellent  and  as  a  mulch,  or  fertilizer.  It  i-  claimed 
i>\  some  to  deter  the  striped  cucumber  beetle;  others  report  that  it  is 
not  effect  i\  o  for  this  beet  le. 

A  successful  fumigation  or  vaporization  of  a  cucumber  house 
infested  with  the  melon  aphis  was  made  also  in  June,  UK)6,  :ii  Ana 
costia,  1 '.  (  .  \  (I  i  tie  re  mi  preparation  was  used,  ami  66,000  cubic  feet 
of  greenhouse  space  was  fumigated,  22  ounces  of  the  liquid,  <>r  I  ounce 
to  3,000  cubic  feet,  being  employed  The  work  was  under  the  writer's 
direction  and  conducted  h\  Mr.  I.  .1.  Condit,  with  the  cooperation  of 
Mr.  .1.  \\  .  Bryan,  owner  of  the  house.  At  the  end  of  an  hour  and 
fifteen  minutes,  when  the  ventilators  were  opened  and  the  greenhouse 
aired,  the  aphides  were  found  dead  and  dying,  and  the  cucumbers 
were  unharmed.  Bight  evaporators  were  used  in  this  instance,  each 
holding  a  little  less  than  3  ounces  of  the  liquid.  It  i-  mite  probable 
that  a  considerably  smaller  amount  of  the  preparation,  -a\  1  ounce  to 
5,000  tail )ic  feet,  with  an  all-night  exposure,  would  have  accomplished 
the  -aim'  object  The  cost  <>f  fumigation  is  not  above  (2.50  for  a 
house  containing  64,000  cubic  feet. 

C.\i  noN.  Before  fumigating  an  entire  greenhouse  with  anj  sub- 
Btance  a  preliminary  test  i-  always  advisable  to  guard  against  acci- 
dents and  to  avoid  waste  of  material.  In  the  case  of  one  liquid 
tobacco  fumiganl  used  at  Washington,  the  preliminary  t'"-t  showed 
that,  employed  at  the  strength  advised  by  tin-  manufacturers  (/.  .. 
without  dilution),  it  ignited  in  the  evaporating  pan  instead  of  vaporiz- 
ing. This  trouble  was  obviated  by  diluting  the  fumigant  with  half  it- 
amount  of  water,  the  further  precaution  being  taken  of  placing  a  wire 
gauze  lie  nea  tli  the  pan  and  over  the  flame.  In  the  case  of  some  alcohol 
lamps  used  for  this  purpose  the  flame  is  apt  to  be  too  strong,  espe- 
cial!} if  placed  too  near  tin1  evaporator.  This  causes  the  glass  to  break. 
l*>ra--  or  other  metal  lamp-  are  therefore  preferable.  Unless  the 
lamp-  and  wicks  are  of  good  quality  and  tit  properly,  the  alcohol  i- 
apt  to  ooze  Out  around  the  cork  and  bum  on  the  sides  <<\'  the  lamp  and 

thus,  al-o.  cause  breakage. 

A-  a  general  rule  it  i-  besl  not  to  fumigate  in  bright  9unlight,  and 
not  when  delicate  foliage  or  flowers  have  globules  of  water  on  them. 

BPH  M  IN'-    METHODS. 

Kerosen<  emulsion  <'/"/  soap  solutions.  The  melon  aphis  could  he 
much  more  readily  dealt  with  if  it  were  not  for  it-  unfortunate  ha  Wit  of 
feeding  on  the  under  surface  of  leai  es  which  are  often  badly  curled, 
a-  -how  n  in  figure  1  and  for  the  further  fact  that  in  large  fields,  par- 
ticularly late  in  the  -ea-on  when  the  lea\e-  are  large,  the  vines  gTOW 
so  closely  together,  frequently  becoming  interlaced,  that  spraying  by 
ordinary  means  is  impracticable.  (Jnderspraying  i-  an  absolute  neces 
-it\  .  and  a  sprayer  should  he  used  lifted  with  an  upturned  elbow  and  a 


u 


nozzle  of  tbe  Vermorel  type  to  secure  this  effect.     An  dhow  designed 
for  this  purpose  is  shown  in  figure  5. 

Kerosene-soap  emulsion,  the  standard  remedy  for  aphides,  is  the  best 
insecticide  for  spraying  purposes,  but  various  soap  solutions  are  used 
both  for  the  melon  and  pea  aphides.  They  are  diluted  with  *>  to  <S  parts 
of  water.  The  emulsion  and  soap  washes  are  of  particular  value  when 
the  plants  are  small,  as  then  the  aphides  can  be  more  readily  reached 
than  when  the  leaves  have  grown  to  larger  size:  and.  to  repeat,  if  inju- 
ries are  to  he  averted  the  insect  should  be  cheeked  on  its  first  appear- 
ance, not  alone  on  cucumbers,  melons, squashes,  or  whatever  the  main 
crop  may  be,  but  upon  all  neighboring  plants  which  may  harboi  the 
insect,  including  beds  of  strawberry  or  groves  of  orange  tree-. 

Kerosene  soap  emulsion  is  prepared  by  combining  2  gallons  of  kero- 
sene, one-half  pound  of  whale-oil  soap,  or  1  quart  of  soft  soap,  with  1 
gallon  of  water.  The  soap  is  dissolved  in  boiling  water  and  then 
poured  while  still  boiling  hot  (away  from  the  fire)  into  the  kerosene. 
The  mixture  is  then  churned  rapidly  for  about  live  minutes,  pumping 
the  liquid  back  upon  itself  by  means  of  a  force  pump  and  direct-dis- 
charge nozzle  throwing  a  strong  stream.  At  the 
end  of  this  time  the  mixture  will  have  become  of 
the  consistency  of  thick  cream.  Properly  prepared, 
an  emulsion  will  keep  almost  indefinitely,  and 
should  be  diluted  only  as  needed  for  use.  For 
most  species  of  aphides  the  staple  emulsion  should 
be  diluted  with  from  10  to  20  parts  of  water.  In 
the  preparation  of  kerosene  emulsion  a  force  pump 
is  a  necessity,  since  if  not  made  according  to 
directions  a  perfect  emulsion  is  not  formed.  There  is  then  danger  of 
injury  to  the  plants  by  the  kerosene,  as  also  useless  waste.  There  ifl 
danger  and  waste,  too.  if  the  insecticide  is  not  applied  by  means  of  a 
fine  nozzle  in  the  form  of  a  spray,  which  should  be  line  and  mist-like, 
or  "like  a  fog."  as  some  one  has  aptly  exprest  it.  It  should  be 
sprayed  only  for  a  long  enough  time  to  cover  the  plants,  otherwise 
the  liquid  forms  into  globules  and  runs  off.  Figure  <>  illustrates 
the  method  of  operating  a  knapsack  sprayer  so  as  to  produce  an 
underspraying. 

Spraying  with  water. — 'Where  a  lew  plants  only  are  to  be  protected, 
and  it  is  possible  to  direct  a  strong  stream  of  water  upon  them  from  a 
garden  hose,  syringe,  or  spraying  machine,  so  as  to  wash  off  the 
insects,  the  aphis  can  be  materially  checked  without  the  use  of  other 
materials.  Such  of  the  insects  as  come  into  direct  contact  with  a  stiff 
spray  are  unable  to  survive,  while  others  that  are  dislodged  from  the 
plants  do  not  succeed  in  returning.  Many  are  wingless  during  the 
greater  part  of  the  season  and  unable  to  crawl  any  distance,  particu- 
larly if  the  ground  be  dry  and  hot. 


Fig.  5.— Elbow  attach 
ment  fur  underspray 
ing.    Reduced. 


'  '  Ml  i;  M     MM  now 

.   ^"^l  methods  give  grt*te«i  promise  as  re, lies.     Clean  garden 

mg  or  farming  with  Pall  plowing  should  always  be  followed   as  these 

,(;r"  "  "^valuable  meaBure  of  prevent! I  injur3   by  this  and 

othe,  ...sects  that  are  present   in  the  fields.     A as  the  crop  is  ofl 

™»mn.nto  should  be  gathered  and  burned.     All  weeds  in  the  vicing 
should   he  kepi  downthruoul   the  year,  including   late  fall  and  carl 

y™*«n«.M  hasalreadj  I n   shown,  I ...,„, weeds  of  the 

he,d  ;,1h1  garden  are  available  a-  alternate 
,'""'1  P^ts  and  serve  as  the  hibernating 
quarters  of  the  aphides,  which  feed  more  or 
less  thruout  the  warmer  periods  of  winter. 
On  weeds  the  insects  can  be  found  feeding, 
'"  ;1  climate  like  that  of  the  District  of 
Columbia,  until  January,  "even  after  heai  \ 
frosts  or  snow,"  and  again  in  March. 

'  OHTBOl  in     mii,,n     iPHia     n     S  IT1  RAJ 

I  \nm\ 

The   possible   control   of    this    pest   with 
the  assistance  of  its  natural  enemies,  aided 

by     a     trap      nop. 

if   proposed  i>\ 

.Mi.  Sanborn,  who 

has    placed    at    the 

writer's  d  isposal 

advance   sheets  of 

lii^  publication    in 

which  this  method 

i-  described. 

Rape,  which  isof 
value  for  hog  and 
sheep  pasture.  is 
tli«   crop   adviy 

Kale   or  mustard     «*»  •     R  r  .pplylng 

should    serve     the 

plant 'l!r|,OM''     Thl8method  ^^  ^  the  fall  when  the  trap  cn>p  is 

J^bage ^  aphis ,  {Aphis  bra :,   L.)  is  cl ly  related  to,   but 

M"»,  •!-""<•'    fron^the   melon  aphis.     It  winters  over  on   .1,,  trap 
'•--.-.■,i  vears  the  writer  has^obeerved  that  th«  ,.,,,.,., 

tin    , ,  ■   ,         7,  u  '"  ,,hwtrated  '"  ^""'"  ■•:  and  the  idea  of  employuTg 

Hu>  ,„...,„>  ...at,n,,„ni:,h,„a,„nil  .,„..„.  ted  to  the  writer  in  19$ 


UNIVERSITY  OF  FLORI 


16 

■  i ii r*.» ...  „ ^jg  j "^6  4648 

crop  and  attacks  it  early  in  spring,  when,  umesa  me  natural  enemies 
cnmc  to  the  fore,  it  multiplies  in  great  abundance.  In  the  writer's 
experience  .the  ladybirds  and  other  enemies  soon  gain  the  ascendancy 
and  become  so  abundant  that  they  are  forced  to  migrate  for  food. 
The  trap  crop  will  ordinarily  remain  in  condition  to  sustain  aphides 
and  their  enemies  until  melons  or  other  crops  susceptible  to  melon- 
aphis  damage  have  past  the  danger  stage  and  are  ripening. 

The  farmer  may  exercise  his  own  judgment  in  regard  to  the  loca- 
tion of  the  trap  crop.  The  writer  believes  that  the  greatest  advanl 
would  accrue  from  planting  three  or  more  rows  of  rape  or  kale  on 
each  side  and.  in  the  case  of  fields  of  more  than  4  or  5  acres,  by  plant- 
ing additional  rows  between.  Planted  on  all  sides,  the  trap  crop  will 
attract  aphides  and  their  enemies  from  every  direction,  and  this  result 
will  he  facilitated  by  permitting  the  growth  of  weed-  between  the 
rows.  In  fact,  weeds  are  a  desideratum  in  these  operations,  since 
they  furnish  the  best  natural  hibernating  place-  for  the  ladybirds  and 
similar  beneficial  insects.  It  is  advisable  also  to  place  boards,  loose 
bark,  or  hollow  logs  about  the  margins  of  the  fields  to  secure  better 
facilities  for  hibernation.  A-  fast  as  one  crop  of  rape,  or  whatever 
is  used,  matures,  or  its  growth  is  stopt  by  the  aphides  (a-  might 
sometimes  happen),  another  planting  should  be  made  so  a-  t •  >  keep  a 
constant  supply  of  cabbage  aphides  on  hand  that  the  natural  enemies 
may  not  migrate  to  other  quarters. 


CONCLUSION. 


Many  of  the  remedies  that  have  been  indicated  as  of  service  in  the 
control  of  the  melon  aphis  (with  the  exception  of  the  last)  operate 
against  most  other  cucurbit  insect-,  several  species  of  which  are 
usually  present.  Thus  the  kerosene  emulsion  and  soap  solutions  kill 
young  squash  hugs  and  act  as  deterrents  to  most  other  insects,  and 
bisulfid  of  carbon  will  kill  other  soft-bodied  insects  besides  the  aphides, 
while  fall  plowing  and  clean  cultural  methods  are  valuable  in  destroy- 
ing the  squash-vine  borer.  Tobacco  fumigation,  however,  ha-  little 
effect  on  these  other  insects  as  they  occur  in  the  field. 

Approved: 

James  Wilson, 

S(  crt  tary  of  .  igriculturi . 

Washington,  I).  C,  Xoccmbcr  /.£,  1906. 

O 


